U.S. patent application number 15/341496 was filed with the patent office on 2017-05-11 for sound generator for mounting on a vehicle to manipulate vehicle noise.
The applicant listed for this patent is Eberspacher Exhaust Technology GmbH & Co. KG. Invention is credited to Jan KRUGER, Manfred NICOLAI, Thomas SCHMIDT.
Application Number | 20170133003 15/341496 |
Document ID | / |
Family ID | 57209261 |
Filed Date | 2017-05-11 |
United States Patent
Application |
20170133003 |
Kind Code |
A1 |
NICOLAI; Manfred ; et
al. |
May 11, 2017 |
SOUND GENERATOR FOR MOUNTING ON A VEHICLE TO MANIPULATE VEHICLE
NOISE
Abstract
A sound generator (100) mounts on a vehicle to manipulate
vehicle noise originating from a vehicle operated by an internal
combustion engine. The sound generator (100) includes a casing
(110), a loudspeaker (120), and at least one pressure compensation
valve (130). The loudspeaker (120) and the casing (110) together
thereby enclose a volume (115). Further, the pressure compensation
valve (130) couples the volume (115) enclosed by the loudspeaker
(120) and the casing to an outside of the casing (110). The
pressure compensation valve (130) thereby extends through a plane
in which the loudspeaker (120) is located. A system (200) for
manipulating sound waves propagating through exhaust systems of
vehicles driven by an internal combustion engine uses the above
sound generator (100).
Inventors: |
NICOLAI; Manfred;
(Esslingen, DE) ; SCHMIDT; Thomas; (Steinheim,
DE) ; KRUGER; Jan; (Neuhausen, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Eberspacher Exhaust Technology GmbH & Co. KG |
Neunkirchen |
|
DE |
|
|
Family ID: |
57209261 |
Appl. No.: |
15/341496 |
Filed: |
November 2, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F01N 1/065 20130101;
H04R 9/06 20130101; G10K 2210/128 20130101; H04R 2499/13 20130101;
G10K 2210/127 20130101; F01N 13/1866 20130101; F01N 1/166 20130101;
G10K 11/178 20130101; G10K 11/17883 20180101; G10K 11/17857
20180101 |
International
Class: |
G10K 11/178 20060101
G10K011/178; F01N 1/16 20060101 F01N001/16; F01N 1/06 20060101
F01N001/06 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 6, 2015 |
DE |
10 2015 119 191.1 |
Claims
1. A sound generator for mounting on a vehicle to manipulate
vehicle noise, the sound generator comprising: a casing; a
loudspeaker, the loudspeaker and the casing together enclosing a
volume and the loudspeaker extending along a loudspeaker plane; and
at least one pressure compensation valve, the pressure compensation
valve coupling the volume enclosed by the loudspeaker and the
casing with an outside of the casing and the pressure compensation
valve extending through the loudspeaker plane.
2. A sound generator according to claim 1, wherein: the at least
one pressure compensation valve comprises a valve body and a valve
head; the valve body has a first end with a first opening formed
therein that opens to the outside of the casing, and a second end
with a second opening accommodating the valve head, the valve head
being disposed inside the volume enclosed by the loudspeaker and
the casing; and the valve head includes a through hole for air.
3. A sound generator according to claim 2, wherein the at least one
pressure compensation valve is positioned in the casing and the
valve body is dimensioned such that the valve head is disposed
opposite the loudspeaker plane and is located at a maximum distance
to the loudspeaker plane.
4. A sound generator according to claim 2, wherein the first
opening of the valve body is located in the loudspeaker plane.
5. A sound generator according to claim 2, wherein the valve body
includes an increased diameter section between the first opening
and the second opening and a diameter of the increased section of
the valve body is increased with respect to a diameter of the first
opening or the second opening or both the the first opening and the
second opening.
6. A sound generator according to claim 5, wherein the increased
diameter section is fully or in part located inside the casing.
7. A sound generator according to claim 2, wherein a volume
enclosed by the valve body between the first opening and the second
opening amounts to between 1% and 20% of the volume enclosed by the
loudspeaker and the casing.
8. A sound generator according to claim 2, wherein a volume
enclosed by the valve body between the first opening and the second
opening amounts to between 4% and 15% of the volume enclosed by the
loudspeaker and the casing.
9. A sound generator according to claim 2, wherein the valve head
comprises a membrane in a valve head interior, the membrane being
permeable to air and impermeable to water and closing the through
hole.
10. A sound generator according to claim 2, wherein the through
hole of the valve head is a throttle enabling, at a constant
pressure difference of 300 Pa and a passage of more than 2 liters
of air per hour and less than 10 liters of air per hour.
11. A sound generator according to claim 2, wherein the through
hole of the valve head is a throttle enabling, at a constant
pressure difference of 300 Pa and a passage of more than 3 liters
of air per hour and less than 9.0 liters of air per hour.
12. A sound generator according to claim 2, wherein the through
hole of the valve head is a throttle enabling, at a constant
pressure difference of 300 Pa and a passage of more than 4 liters
of air per hour and less than 8 liters of air per hour.
13. A sound generator according to claim 1, wherein the valve body
is formed integrally with the casing.
14. A sound generator according to claim 2, wherein the loudspeaker
comprises: a loudspeaker basket; a membrane retained airtight by
the loudspeaker basket; a permanent magnet retained by the
loudspeaker basket; a voice coil retained by a voice coil carrier,
the voice coil being located in a constant magnetic field generated
by the permanent magnet and the voice coil being coupled to the
membrane wherein: the loudspeaker basket is coupled airtight to the
casing; and the valve body penetrates the loudspeaker basket or the
valve body is coupled airtight to the loudspeaker basket with the
first opening of the valve body being aligned with an opening
formed in the loudspeaker basket.
15. A sound generator according to claim 14, wherein the valve body
is integrally formed with the loudspeaker basket.
16. A sound generator according to claim 1, wherein the loudspeaker
comprises: a loudspeaker basket; a membrane retained airtight by
the loudspeaker basket; a permanent magnet retained by the
loudspeaker basket; and a voice coil retained by a voice coil
carrier, the voice coil being located in a constant magnetic field
generated by the permanent magnet and being coupled to the
membrane, wherein: the loudspeaker basket is coupled airtight to
the casing; and the loudspeaker plane is oriented orthogonally to a
main emission direction of sound emitted from the loudspeaker and
is positioned between the voice coil and a section of the membrane
furthermost from the voice coil.
17. A system for manipulating sound waves propagating through an
exhaust system of a vehicle driven by an internal combustion
engine, the system comprising: a controller connected to an engine
controller of the vehicle by a control line or built-in into the
engine controller of the vehicle; and at least one sound generator
comprising: a casing; a loudspeaker, the loudspeaker and the casing
together enclosing a volume and the loudspeaker extending along a
loudspeaker plane; and at least one pressure compensation valve,
the pressure compensation valve coupling the volume enclosed by the
loudspeaker and the casing with an outside of the casing and the
pressure compensation valve extending through the loudspeaker
plane; a control line connecting the loudspeaker to the controller,
wherein the controller is configured to generate a control signal
based on signals received from the engine controller and to output
the control signal to the loudspeaker via the control line, the
control signal being adapted to cancel the sound waves propagating
through the exhaust system of the vehicle to some extent or
completely, when the control signal is used to operate the
loudspeaker.
18. A system according to claim 17, wherein: the at least one
pressure compensation valve comprises a valve body and a valve
head; the valve body has a first end with a first opening formed
therein that opens to the outside of the casing, and a second end
with a second opening accommodating the valve head, the valve head
being disposed inside the volume enclosed by the loudspeaker and
the casing; and the valve head includes a through hole for air.
19. A system according to claim 18, wherein the valve head
comprises a membrane in a valve head interior, the membrane being
permeable to air and impermeable to water and closing the through
hole.
20. A system according to claim 18, wherein the loudspeaker
comprises: a loudspeaker basket; a membrane retained airtight by
the loudspeaker basket; a permanent magnet retained by the
loudspeaker basket; a voice coil retained by a voice coil carrier,
the voice coil being located in a constant magnetic field generated
by the permanent magnet and the voice coil being coupled to the
membrane wherein: the loudspeaker basket is coupled airtight to the
casing; and the valve body penetrates the loudspeaker basket or the
valve body is coupled airtight to the loudspeaker basket with the
first opening of the valve body being aligned with an opening
formed in the loudspeaker basket.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of priority under 35
U.S.C. .sctn.119 of German Application 10 2015 119 191.1 filed Nov.
6, 2015, the entire contents of which are incorporated herein by
reference.
FIELD OF THE INVENTION
[0002] The invention relates to a sound generator for mounting on a
vehicle to manipulate vehicle noise. The vehicle may be a vehicle
driven by an internal combustion engine or electrically, and in
particular a motor vehicle. The sound generator may, in particular,
be part of a system for manipulating sound waves traveling through
exhaust systems of vehicles driven by an internal combustion
engine.
BACKGROUND OF THE INVENTION
[0003] Irrespective of the internal combustion engine type (for
example piston engine, rotary engine or free-piston engine), noises
are generated due to the cycle of strokes (notably the induction
and compression of an air fuel mix, power, and exhaust of the
combusted air fuel mix). Part of the noise propagates through the
combustion engine in the form of structure-borne noise and is then
emitted from the combustion engine's outside in the form of
airborne noise. Another part of the noise travels, together with
the combusted air fuel mix, in the form of airborne noise through
an exhaust system that is in fluid communication with the internal
combustion engine. The noise traveling through the exhaust system
in the form of airborne noise is called exhaust noise.
[0004] Other noises generated by vehicles driven by an internal
combustion engine are the tire rolling noise on the roadway surface
and the aerodynamic noise due to air displacement while the vehicle
is moving.
[0005] These noises are often regarded as being harmful.
Accordingly, there are statutory provisions for noise control to be
observed by manufacturers of vehicles driven by internal combustion
engines. The statutory provisions usually specify a maximum
allowable sound pressure for a vehicle in operation. In addition,
manufacturers try to give a distinctive noise emission to their
vehicles driven by internal combustion engines, fitting the image
of the respective manufacturer and favored by their customers. With
state of the art small-displacement engines, it is no longer
possible to achieve such a distinctive noise emission in a natural
way.
[0006] Noise propagating through the internal combustion engine in
the form of structure-borne noise can be deadened well and is
therefore generally not an issue with regard to noise control.
[0007] Exhaust noise that propagates through an exhaust system of
an internal combustion engine in the form of airborne sound,
together with the combusted air fuel mix, is mitigated by mufflers
located upstream of the discharge opening and, when present,
downstream of catalytic converters. Respective mufflers may
operate, for instance, according to at least one of the absorption
and reflection principle. The drawback of both modes of operation
is that they require a comparatively large volume, and build up a
relatively high resistance to the combusted air fuel mix, thereby
reducing the overall efficiency of the vehicle and increasing its
fuel consumption.
[0008] For quite some time, so-called anti-noise systems have been
developed as an alternative or complement to mufflers which add
electro acoustically generated anti-noise to airborne noise
generated in the internal combustion engine and traveling through
the exhaust system. Respective anti-noise systems usually use a
so-called Filtered-x Least Mean Squares (FxLMS) algorithm that
tries to reduce the noise propagating through the exhaust system to
zero (in the case of noise cancellation) by emitting sound from at
least one sound generator (e.g. a voice coil loudspeaker or a
different acoustic actor) that is in fluid communication with the
exhaust system or to a predetermined threshold (in the case of
active noise manipulation). To achieve complete destructive
interference between the sound waves of the airborne noise
traveling through the exhaust system and the anti-noise generated
with the sound generator, the sound waves from the sound generator
have to have the same amplitude and frequency as the sound waves
propagating through the exhaust system but are shifted by 180
degrees in phase. When the sound waves propagating through the
exhaust system have the same frequency as the sound waves of the
anti-noise generated at the sound generator with their phases
shifted by 180 degrees with respect to each other, but do not
correspond in amplitudes, the sound waves of the airborne noise
propagating through the exhaust system is only mitigated. The FxLMS
algorithm calculates the anti-noise for each frequency band of the
airborne noise propagating through the exhaust system separately by
identifying an appropriate frequency and phasing for two sinusoidal
oscillations that are shifted by 90 degrees with respect to each
other and calculating the required amplitudes for these sinusoidal
oscillations. Anti-noise systems aim at the noise cancellation or
noise manipulation being audible and measurable at least outside
of, but if need be also inside, the exhaust system. Establishing a
control signal for generating a desired anti-noise with a sound
generator is known to a person skilled in the art from documents
U.S. Pat. No. 4,177,874, U.S. Pat. No. 5,229,556, U.S. Pat. No.
5,233,137, U.S. Pat. No. 5,343,533, U.S. Pat. No. 5,336,856, U.S.
Pat. No. 5,432,857, U.S. Pat. No. 5,600,106, U.S. Pat. No.
5,619,020, EP 0 373 188, EP 0 674 097, EP 0 755 045, EP 0 916 817,
EP 1 055 804, EP 1 627 996, DE 197 51 596, DE 10 2006 042 224, DE
10 2008 018 085 and DE 10 2009 031 848. A description of further
details is therefore omitted. In this respect it is noted that the
term "anti-noise" is used in this document to discriminate between
the engineered sound from the sound generator and exhaust noise or
other noises originating from the internal combustion engine. By
itself, the anti-noise is nothing else than ordinary noise (usually
airborne noise).
[0009] Creating noise from anti-noise systems may be implemented by
coupling the sound generator acoustically to the exhaust system. As
an alternative it is also known to mount the sound generator
separately from the exhaust system, e.g. at the underbody of a
vehicle rear, in order to emit the anti-noise from there.
Irrespective of the sound generator being mounted in fluid
communication with the exhaust system or separate from the exhaust
system at a vehicle's underbody, placing the sound generator on the
underbody of a vehicle causes several problems: firstly, the space
available is usually very limited requiring a very compact design
of the muffler, secondly, the sound generator has to be protected
from environmental influences, and in particular from water and
contamination.
[0010] As an example for respective sound generators, a sound
generator for generating anti-noise in order to manipulate sound
waves propagating through an exhaust system of a vehicle driven by
an internal combustion engine is described below with respect to
FIGS. 1A and 1B.
[0011] The sound generator 3 illustrated in the perspective view of
FIG. 1A comprises an inherently stable two-part casing formed by an
upper shell 32 and a lower shell 33 put together in an airtight
manner. The casing houses an electrodynamic loudspeaker 2 and is
connected to an exhaust system via a Y-pipe 1. At the base of the
"Y", the Y-pipe has a port 5 for discharging exhaust gas traveling
through the exhaust system 4 and noise generated by the loud
speaker 2. By having the connection implemented with the Y-pipe,
the thermal stress of the loudspeaker 2 disposed within the sound
generator 3 due to the exhaust gas traveling through the exhaust
system 4 is kept low. This is necessary, because conventional
loudspeakers are configured to be operated in a range up to a
maximum of 200.degree. C. only, while the temperature of the
exhaust gases traveling through the exhaust system 4 may be between
400.degree. C. and 700.degree. C. A pressure compensation valve 36
is disposed on the upper shell 32 of the casing. To protect the
pressure compensation valve 36 positioned on the surface of the
upper shell 32 from being damaged, the upper shell 32 also supports
a cast metal ring 37 surrounding the pressure compensation valve
36. The ring 37 has a slot at its bottom for allowing liquid to
drain off from the region surrounded by the ring 37. Finally, the
upper shell 32 holds a cable bushing 34 through which connecting
wires are fed-through into the inside of the sound generator 3.
[0012] FIG. 1B shows a schematic cross section through the sound
generator 3 of FIG. 1A. As can be seen, the loudspeaker 2 comprises
a voice coil type loudspeaker 2, a permanent magnet 21, and a
bell-mouthed membrane 22 which are together supported by a
loudspeaker basket 23. Hereby, the membrane 22 is connected at its
radial outside to the loudspeaker basket 23 by an elastic surround
(not shown) and comprises at its radial inside a voice coil (not
shown) that moves in bores formed in the permanent magnet 21. By
applying an alternating current to the voice coil, a Lorentz force
is exerted onto the membrane 22 by the voice coil resulting in an
oscillation of the membrane 22. Wires 35 supply the control signals
required for operating the voice coil through the cable bushing 34
disposed on the upper shell 32 of the casing. At its radial
outside, the loudspeaker basket 23 is supported by a bell mouth 42
connected to the Y-pipe 1 via a connecting pipe 41. The bell-mouth
42 has to be used in the example shown, since the area of the
loudspeaker's 2 membrane 22 is larger than the cross-sectional area
of the exhaust system 4 in the sound coupling region. The large
area of the membrane 22 is necessary to achieve the required sound
energy flux. The bell-mouthed membrane 22 defines an axis of
symmetry forming an angle of 33.degree. with the bottom of the bell
mouth 42. The membrane 22, the surround, a fringe of the
loudspeaker basket 23, and the bell 42 divide the volume enclosed
by the casing into a rear volume 38 that is not in fluid
communication with the Y-pipe 1, and a front volume 39 that is in
fluid communication with the Y-pipe 1. The rear volume 37 is thus
basically sealed and acts as an air cushion onto the membrane 22 of
the loudspeaker 2. The front volume 39 corresponds basically to the
volume enclosed by the bell 42 and is not sealed. Depending on the
(air) pressure in the rear volume 37 being higher or lower than the
(air) pressure in the front volume 39, the rear volume 37 dampens
the membrane 22 to a greater or lesser extent and may also cause a
deflection of the membrane 22 to only one side from its zero
position. Operating the loudspeaker 2 with a respective one-sided
displacement of the membrane 22 from its zero position results in a
considerable reduction of its life expectancy. The pressure
compensation valve 36 ensures that a pressure inside the casing is
approximately the same as a pressure outside of the casing. By
providing the pressure compensation valve 36, the pressure inside
the rear volume 38 is continuously adapted to the pressure present
outside the casing of the sound generator 3. This is supposed to
prevent a one-sided displacement of the membrane 22 from its zero
position.
[0013] A drawback of the above configuration is that the sound
generator's pressure compensation valve frequently functions
unreliably. One reason being that the pressure compensation valve
is easily damaged by impacts from the outside; the other that dust
and water may easily clog the pressure compensation valve making
any pressure compensation impossible. Since pressure compensation
valves are often designed for air to pass through but not for water
to pass through, pressure compensation is often not possible,
particularly when the pressure compensation valve of the sound
generator is located below the surface of a water body.
Consequently, it is often necessary to use a loudspeaker of
increased robustness inside the sound generator. This increases
cost and may, due to the increased rigidity of the membrane
involved therewith, and reduces the acoustic performance of the
loudspeaker at low frequencies.
[0014] In order to solve this problem, DE 10 2013 208 186 A1
suggests to couple the pressure compensation valve to the sound
generator via a long pressure compensation line, allowing the
pressure compensation valve to be placed at any (and thus well
protected) position on the vehicle. This, however, increases the
effort for mounting the sound generator considerably.
[0015] A further problem with the configuration described above is
that, when the exhaust system is submerged into water, an increased
pressure is applied from outside to the membrane. This results in
the membrane no longer oscillating around its rest position but
rather on a plane spaced from this rest position, and thus having
an offset. An oscillation of the offset membrane further results in
the rear volume being pumped out through the pressure compensation
valve.
[0016] The above problems are also present, when the sound
generator is not in fluid communication with the exhaust system
different to the sound generator shown in FIGS. 1A and 1B. Also in
this case the membrane and a casing of the sound generator enclose
a rear volume so that a pressure compensation valve is also
required here. For a sound generator that is not in fluid
communication with the exhaust system there is also an increased
risk of a membrane offset due to an increased outside pressure.
SUMMARY OF THE INVENTION
[0017] It is therefore an object of the present invention to
provide a sound generator for a system for manipulating noises, and
in particular exhaust noise, from vehicles driven by an internal
combustion engine which reliability is improved, particularly with
respect to an immersion of the sound generator into water. The
sound generator is further supposed to be manufactured
cost-efficiently and to be robust in mounting and operation.
[0018] Embodiments of a sound generator for manipulating noises
from a vehicle comprise a casing, a loudspeaker, and at least one
pressure compensation valve. The term "loudspeaker" is hereby
understood as that part of the sound generator that transduces
electrical signals into mechanical oscillations (sound). In
combination with the casing, the loudspeaker encloses a volume.
Thus, this volume, also referred to as rear volume, is confined by
the casing (and in particular by the inner surface of the casing)
and the loudspeaker. To achieve this, the loudspeaker is in
particular coupled to the casing in a gastight manner. The
loudspeaker may thereby be located partly or completely inside the
casing or directly adjacent to the casing. The pressure
compensation valve provides a fluid communication between the
volume enclosed by the loudspeaker together with the casing and an
outside of the casing. The pressure compensation valve is thereby
positioned to extend through a plane in which (along which) the
loudspeaker is disposed. The plane in which the loudspeaker is
disposed may be defined by a loudspeaker membrane or a loudspeaker
basket and oriented, e.g., orthogonal to the main emission
direction of sound emitted from the loudspeaker. Alternatively, the
plane in which the loudspeaker is disposed may, for instance, be
defined by respective fasteners formed at the casing. If the
loudspeaker is a voice coil loudspeaker having a loudspeaker
membrane and a voice coil carried by the loudspeaker membrane, the
plane in which the loudspeaker is located may be any plane
orthogonal to a main emission direction of sound emitted from the
loudspeaker and located between the voice coil and a part of the
loudspeaker membrane furthermost from the voice coil. According to
an embodiment the part of the loudspeaker membrane furthermost from
the voice coil shall be the part of the loudspeaker membrane that
is most remote from the voice coil in a direction of symmetry of
the loudspeaker membrane. According to an embodiment, the part of
the loudspeaker membrane furthermost from the voice coil shall be
the part of the loudspeaker membrane that is connecting the
loudspeaker membrane to a basket of the loudspeaker.
[0019] Since the pressure compensation valve extends through the
plane along which the loudspeaker is disposed, a pressure
difference actually present between the two sides of the
loudspeaker is relieved. The pressure compensation valve thus
enables a particularly precise pressure compensation. Furthermore,
any pumping out of the volume enclosed by the loudspeaker and the
casing by the loudspeaker is avoided when the pressure outside of
the volume enclosed by the loudspeaker and the casing but in front
of the loudspeaker rises.
[0020] According to an embodiment, the casing is made from an
inherently stable solid material like a metal sheet, and in
particular a stainless steel panel, or synthetic material, and in
particular acrylonitrile butadiene styrene (ABS), polyamide (PA),
polylactide (PLA), poly(methyl methacrylate) (PMMA), polycarbonate
(PC), polyethylene terephthalate (PET), polyethylene (PE),
polypropylene (PP), polystyrene (PS), polyether ether ketone
(PEEK), or polyvinyl chloride (PVC). According to an embodiment,
the casing is made either integrally or from several parts.
[0021] According to an embodiment, the casing comprises fastening
eyelets or fastening anchors enabling the casing to be mounted on a
vehicle and in particular on the undercarriage of a vehicle.
[0022] According to an embodiment, the casing is configured for
being coupled to an exhaust system of a vehicle driven by an
internal combustion engine, in particular by using an additional
bell mouth, so as to be brought into fluid communication with
exhaust gas traveling through the exhaust system.
[0023] According to an embodiment, the at least one pressure
compensation valve comprises a valve body and a valve head, thus
being formed from several parts. The valve body comprises a first
end having a first opening formed therein which opens to the
outside of the casing. The valve body comprises also a second end
having a second opening formed therein. The first and second ends
may be located opposite each other. The second opening accommodates
the valve head at the second end of the valve body such that the
valve head seals the second opening. The valve head is located
inside the volume enclosed by the loudspeaker and the casing. The
valve head includes a through hole for air that opens out into the
volume enclosed by the loudspeaker and the casing. The valve body
thus serves to supply the valve head with air from outside the
casing and to introduce the air supplied via the valve head into
the volume enclosed by the loudspeaker and the casing, or to
discharge air received from the volume enclosed by the loudspeaker
and the casing via the valve head into the surroundings of the
casing. Hence, the valve body is (at least not primarily) used for
transmitting airborne sound to the outside of the casing as in the
case of a bass reflex port. For a transmission of sound related air
pressure and air density variations, the ability of the valve head
to let air pass through is not adequate due to the valve head
responding too slowly. Using a pressure compensation valve
constituted by a valve body and a valve head enables a versatile
positioning of the valve head in the volume enclosed by the
loudspeaker and the casing. The valve head may thereby be located
at the position located at the highest point when the sound
generator is mounted to a vehicle with the vehicle being in a
horizontal position. The valve body also provides the pressure
compensation valve with a certain air volume that can be used for a
pressure compensation when the sound generator is immersed into
water. Accordingly, the valve body also serves as an air reservoir.
According to an embodiment, the air reservoir that is formed by the
valve body is distinct from an internal volume of a tubing
connecting the pressure compensation valve to the outside of the
casing of the sound generator; however, this does not prevent the
air reservoir formed by the valve body from working together with
the internal volume of the tubing connecting the pressure
compensation valve to the outside of the casing of the sound
generator. According to an embodiment, the air reservoir that is
formed by the valve body and/or a tubing connecting the pressure
compensation valve to the outside of the casing of the sound
generator is provided fully or in part inside the casing of the
sound generator.
[0024] According to an embodiment, the valve body is made from an
inherently stable solid material like a metal sheet, and in
particular a stainless steel panel, or synthetic material, and in
particular acrylonitrile butadiene styrene (ABS), polyamide (PA),
polylactide (PLA), poly(methyl methacrylate) (PMMA), polycarbonate
(PC), polyethylene terephthalate (PET), polyethylene (PE),
polypropylene (PP), polystyrene (PS), polyether ether ketone
(PEEK), or polyvinyl chloride (PVC). The valve body may, however,
also be made from a flexible material like an elastomer. The valve
body may be formed integrally or in several parts; the valve body
may in particular be made up of a first body of solid material (as
for instance a barrel) and a second body of flexible material (as
for instance a tube), with the inner volumes of both bodies being
in fluid communication with each other. If the valve body is made
of the first and second body, the tubing connecting the pressure
compensation valve to the outside of the casing may be part of the
valve body, according to an embodiment.
[0025] According to an embodiment, the at least one pressure
compensation valve is disposed inside the casing with the valve
body being dimensioned such that the valve body is disposed
opposite to the plane in which the loudspeaker is located and at a
maximum distance to the plane in which the loudspeaker is located.
Since the loudspeaker is usually oriented downwards when the sound
generator is mounted on a vehicle, the positioning of the valve
body enables pressure compensation even when the sound generator is
immersed completely in water. The feature "at a maximum distance"
thereby indicates a positioning, where the valve body is as far
away as possible from the plane in which the loudspeaker is
located, but which still guarantees an adequate operation of the
valve head. According to an embodiment, the feature "at a maximum
distance" should be complied with when the distance between the
valve body and a plane in which the loudspeaker is located (the
loudspeaker extends along a loudspeaker plane) corresponds to at
least 2/3 of a distance between an inner surface of the casing and
the plane, with the distance being measured at a right angle to
this plane.
[0026] According to an embodiment, the loudspeaker is disposed
between the valve head and the first end of the valve body.
Accordingly, the valve body is shaped and dimensioned to allow a
respective positioning of the valve head.
[0027] According to an embodiment, the valve body comprises a
section between the first opening and the second opening, where a
diameter of the valve body is enlarged with respect to a diameter
of the first and/or second opening. The thus formed broadening of
the valve body constitutes an air reservoir that can be used for
pressure compensation. According to an embodiment, the air
reservoir that is formed by the broadening of the valve body is
distinct from an internal volume of a tubing connecting the
pressure compensation valve to the outside of the casing of the
sound generator; this does not exclude that the air reservoir that
is formed by the broadening of the valve body acts in combination
with the internal volume of the tubing connecting the pressure
compensation valve to the outside of the casing. According to an
embodiment, the air reservoir that is formed by the broadening of
the valve body is provided fully or in part inside the casing of
the sound generator. According to an embodiment, an inner diameter
of the valve body is compared with an inner diameter of the first
and/or second opening.
[0028] According to an embodiment, the volume enclosed by the valve
body between the first opening and the second opening amounts to
between 1% and 20% or between 4% and 15% of the volume enclosed by
the loudspeaker and the casing. A respective volume attunement
usually guarantees a sufficient pressure compensation even when the
sound generator is completely immersed into water.
[0029] According to an embodiment, the valve head comprises a
membrane in its interior, the membrane being permeable to air and
impermeable to water, and closing the through hole of the valve
head. Respective membranes are known to a person skilled in the
art; they may, for example, be made from acrylate copolymers.
[0030] According to an embodiment, the through hole of the valve
head forms a throttle enabling, for a constant pressure difference
of 300 Pa, a passage of more than 2 liters of air per hour and less
than 10 liters of air per hour, or of more than 3 liters of air per
hour and less than 9 liters of air per hour, or of more than 4
liters of air per hour and less than 8 liters of air per hour. The
constant pressure difference is thereby used to determine the rate
of flow of the throttle only. With the sound generator being in
operation, the pressure difference is not constant.
[0031] According to an embodiment, the loudspeaker itself is
gastight.
[0032] According to an embodiment, the loudspeaker comprises a
loudspeaker basket, a membrane retained by the loudspeaker basket
in an airtight manner, a permanent magnet retained by the
loudspeaker basket, and a voice coil retained by the voice coil
carrier. Thereby, the voice coil is positioned in a constant
magnetic field created by the permanent magnet and connected to the
membrane. In other words, the loudspeaker may be a voice coil
loudspeaker. The loudspeaker is further coupled to the casing in an
airtight manner. Furthermore, the valve body may extend through the
loudspeaker basket. Alternatively, the valve body may be coupled to
the loudspeaker basket in an airtight manner with the first opening
of the valve body being aligned with an opening formed in the
loudspeaker basket. Accordingly, the first opening of the valve
body may be positioned in the same plane, where also the membrane
or the loudspeaker basket of the loudspeaker are located.
[0033] The membrane may for instance be funnel-shaped, or
spherically-dome-shaped, or have a non-developable NAWI-shape, as
is usual for voice coil loudspeakers. The membrane may further be
coupled to the loudspeaker basket by an airtight surround.
Non-developable, bell-mouthed, or spherically-dome-shaped membranes
are particularly rigid and enabling the membrane to move uniformly
over its entire surface. Alternatively, also a conical membrane
will do.
[0034] According to an embodiment, the membrane is airtight and
coupled to the loudspeaker basket by an airtight surround. This
allows an adjustment of the membrane's oscillation behavior by an
appropriate material selection and dimensioning of the surround.
According to an embodiment, surround and membrane are further made
from different materials.
[0035] According to an embodiment, the loudspeaker basket carries a
centering device, and in particular a centering spider, coupled to
the voice coil carrier or to the membrane in the region of the
voice coil carrier. It is emphasized that the centering device may
be expendable, when the voice coil is guided inside the permanent
magnet generally frictionless.
[0036] According to an embodiment, the membrane is made from metal,
and in particular from aluminum or titanium, or from synthetic
material, and in particular from aromatic polyamides.
[0037] According to an embodiment, the loudspeaker is coupled to a
bell mouth located inside the casing in an airtight manner. Thus,
inside the casing, also the bell mouth confines the volume enclosed
by the loudspeaker and the casing. The first opening of the valve
body may then be aligned with an opening formed in the bell mouth.
The bell mouth may be configured for being arranged in fluid
communication with an exhaust system of a vehicle driven by an
internal combustion engine.
[0038] According to an embodiment, the valve body is formed
integrally with the loudspeaker basket or the casing or permanently
fixed to the loudspeaker basket or the casing. A portion of the
loudspeaker basket or of the casing may thus form a wall of the
valve body.
[0039] According to an embodiment, the volume enclosed by the
loudspeaker and the casing is, except for the pressure compensation
valve, enclosed in an airtight manner (enclosed airtight).
[0040] According to an embodiment, the casing of the sound
generator is formed in one piece. According to an alternative
embodiment, the casing of the sound generator is composed of an
upper shell and a lower shell airtightly coupled to the upper
shell. The upper shell and/or the lower shell may thereby have at
least one airtight passage for a control line connected with the
loudspeaker.
[0041] According to an embodiment, the at least one pressure
compensation valve is fully contained inside the casing of the
sound generator.
[0042] Embodiments of a system for manipulating sound waves
propagating through exhaust systems of vehicles driven by an
internal combustion engine comprise a controller either configured
for being coupled to an engine control unit of the vehicle by a
control line or built-in into the engine control unit of the
vehicle, and at least one sound generator as described above. A
control line then connects the loudspeaker of the at least one
sound generator with the controller. The controller is further
configured to generate a control signal based on signals received
from the engine control unit and to output the control signal via
the control line to the loudspeaker. The control signal is thereby
adapted to cancel the sound waves propagating through the exhaust
system of the vehicle completely or to some extent, when the
control signal is used to operate the loudspeaker.
[0043] Embodiments of a motor vehicle comprise an internal
combustion engine having an engine controller, an exhaust system in
fluid communication with the internal combustion engine, and the
system described above. The at least one sound generator of the
system is thereby in fluid communication with the exhaust system.
Further, the controller of the system is connected with the engine
controller of the vehicle's internal combustion engine.
[0044] In this context, it is noted that the terms "including",
"comprising", "containing", "having" and "with", as well as
grammatical modifications thereof used in this description and the
claims for listing features, are generally to be considered to
specify a non-exhaustive listing of features such as method steps,
components, ranges, dimensions or the like, and do by no means
preclude the presence or addition of one or more other features or
groups of other or additional features.
[0045] Further features of the invention will be apparent from the
following description of exemplary embodiments together with the
claims and the Figures. In the Figures, equal or similar elements
are assigned equal or similar reference signs. It is noted that the
invention is not limited to the configurations of the exemplary
embodiments described herein, but defined by the scope of the
claims enclosed. Embodiments according to the invention may in
particular implement individual features in different numbers and
combination than the examples described below. The various features
of novelty which characterize the invention are pointed out with
particularity in the claims annexed to and forming a part of this
disclosure. For a better understanding of the invention, its
operating advantages and specific objects attained by its uses,
reference is made to the accompanying drawings and descriptive
matter in which preferred embodiments of the invention are
illustrated.
BRIEF DESCRIPTION OF THE DRAWINGS
[0046] In the drawings:
[0047] FIG. 1A is a schematic perspective illustration of a sound
generator of a system for manipulating sound waves propagating
through exhaust systems of vehicles driven by an internal
combustion engine according to the prior art;
[0048] FIG. 1B is a schematic cross-section through the sound
generator of FIG. 1A;
[0049] FIG. 2A is a schematic cross-section through a sound
generator for mounting on a vehicle to manipulate vehicle noise
according to a first embodiment of the invention;
[0050] FIG. 2B is a schematic cross-section through a sound
generator for mounting on a vehicle to manipulate vehicle noise
according to a second embodiment of the invention;
[0051] FIG. 2C is a schematic cross-section through a sound
generator for mounting on a vehicle to manipulate vehicle noise
according to a third embodiment of the invention;
[0052] FIG. 3A is a schematically drawn cross-section through a
sound generator for mounting on a vehicle to manipulate vehicle
noise according to a fourth embodiment of the invention in a first
operating condition;
[0053] FIG. 3B is a second operation condition of the sound
generator of FIG. 3A;
[0054] FIG. 3C is a third operation condition of the sound
generator of FIG. 3A;
[0055] FIG. 3D is a fourth operation condition of the sound
generator of FIG. 3A in a view rotated with respect to FIG. 3A;
[0056] FIG. 4 is a block diagram of a system for manipulating sound
waves propagating through exhaust systems of vehicles driven by an
internal combustion engine according to an embodiment of the
invention; and
[0057] FIG. 5 is a schematic illustration of a motor vehicle having
the system of FIG. 4 built-in.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0058] Referring to the drawings, a sound generator according to a
first embodiment of the invention is described referencing FIG. 2A.
FIG. 2A thereby shows a cross-section through the sound generator
100 in a schematic view.
[0059] The sound generator 100 shown in FIG. 2A comprises a casing
110 formed from a lower shell 113 and an upper shell 112 coupled to
the lower shell 113 in an airtight manner. Both, the lower shell
113 and the upper shell 112 are made from a stainless steel
panel.
[0060] The lower shell 113 of the casing 110 includes a casing
aperture 111 and receives a bell mouth 140 also made from a
stainless steel panel. In the region of the casing aperture 111 an
outside of the bell mouth 140 is coupled to the lower shell 113 of
the casing 110 in an airtight manner. An opening of the bell mouth
140 is aligned with the casing aperture 111 of the sound generator
100. The bell mouth 140 of the embodiment illustrated is configured
for being coupled to an exhaust system as shown in FIG. 1A for a
prior art sound generator. The bell mouth 140 is coupled to a
loudspeaker basket 123 of a voice coil loudspeaker 120 received in
the casing 110 and made from sheet steel in an airtight manner.
Accordingly, the loudspeaker basket 123 is coupled to the casing
110 via the bell mouth 140 in an airtight manner.
[0061] The voice coil loudspeaker 120 comprises a permanent magnet
121 made from a neodymium iron boron alloy and a non-developable
bell mouthed membrane 122 made from synthetic material, both of
which are carried by the loudspeaker basket 123. Thereby, the bell
mouthed membrane 122 is at the radial outside of its base area
coupled to the loudspeaker basket 123 in an airtight manner by an
elastic surround 126 (see FIG. 3A) made from synthetic material.
The top face of the bell mouthed membrane 122 is centrally sealed
by a synthetic material covering cap in an airtight manner. In the
region of the covering cap, a voice coil carrier 125 (see FIG. 3A)
carrying the voice coil (not shown) is fixed to the membrane 122.
The voice coil is positioned in a constant magnetic field generated
by the permanent magnet 121. The permanent magnet 121 comprises
respective recesses for this. When an alternate current is applied
to the voice coil, the voice coil exerts, due to the Lorentz force,
a force onto the membrane 122 causing it to oscillate. The current
is supplied to the voice coil by means of control lines (only shown
in FIG. 1A) passing into the inside of the sound generator 100
through an airtight cable bushing (only shown in FIG. 1A) at the
upper shell 122 of the casing 110.
[0062] The voice coil loudspeaker 120 and the bell mouth 140
separate a volume 114, that is in fluid communication with an
exhaust system via the bell mouth 140 and the casing aperture 111
of the sound generator 100, from a volume 115, that is confined by
the upper shell 112 and the lower shell 113 of the casing 110 and
also an outside of the bell mouth 114 and in the following referred
to as rear volume, in an airtight manner. Accordingly, the voice
coil loudspeaker 120 with the bell mouth 123 and the casing 110
together define an enclosed rear volume 115 separated from the
atmosphere or the exhaust system by the membrane 122 of the voice
coil loudspeaker 120 and a part of the loudspeaker basket 123.
[0063] A pressure compensation valve 130 is received inside the
casing 110 of the sound generator 100 for enabling a pressure
compensation between this enclosed rear volume 115 and the volume
114 at the other side of the membrane 122 of the voice coil
loudspeaker 120. The pressure compensation valve 130 is composed of
a valve body and a valve head 132. The valve body is not shown for
the embodiment of FIG. 2A, since it is an integral part of a
housing of the valve head 132. The pressure compensation valve 130
thus penetrates a portion of the loudspeaker basket 123 of the
voice coil loudspeaker 120. Hence, the pressure compensation valve
130 extends through the plane in which the membrane 122 of the
voice coil loudspeaker 12 is positioned with respect to the casing
110.
[0064] The valve head 132 of the pressure compensation valve 130
includes a through hole 135 for air operating like a throttle. A
membrane 136 is disposed inside the through hole 135, the membrane
being permeable to air and impermeable to water. In the embodiment
illustrated, the through hole 135 of the valve head 132 of the
pressure compensation valve 130 is dimensioned to allow for a
passage of 7.0 liters of air per hour at a constant pressure
difference of 300 Pascal between the enclosed rear volume 115 and
the volume 114 separated therefrom at the other side of the voice
coil loudspeaker 120. The pressure compensation valve 130 is thus
too slow to respond to variations in the air pressure generated
inside the sound generator 100 by oscillations of the membrane 122
of the voice coil loudspeaker 120. It is noted that the constant
pressure difference of 300 Pascal mentioned above is used to
determine the flow rate through the pressure compensation valve
only; in operation, the pressure difference varies however, and is
reduced by the pressure compensation valve 130 continuously.
[0065] A second embodiment of the invention is discussed below
referencing FIG. 2B. To avoid any repetitions thereby, only
differences to the above first embodiment are addressed, and for
the rest reference is made to the explanations of the first
embodiment.
[0066] The sound generator 100 of the second embodiment differs
from the sound generator 100 of the first embodiment by the
pressure compensation valve 130 comprising a valve body 131
distinct from the valve head 132.
[0067] In the embodiment shown, the valve body 131 made in two
parts from an elastomer includes a tubing and a barrel. The barrel
is in fluid communication with the tubing. At its end facing away
from the barrel, the tubing has a first opening 133 penetrating the
loudspeaker basket 123 to open into the volume 114. Further, a
second opening 134 is formed at the end of the tubing facing away
from the barrel that accommodates the valve head 132 and is thus
closed by the valve head 132. The through hole 135 formed in the
valve head 132 opens into the enclosed rear volume 115. Between the
first opening 133 and the second opening 134, the valve body 131
hence comprises a section 137 formed by the barrel (see FIG. 3A)
wherein a diameter of the valve head 131 is increased with respect
to a diameter of the first opening 133. The valve body 131 thus
provides a volume in its interior that amounts, in the embodiment
shown, to 5% of the rear volume 115 and enables a compensation of
pressure differences between the two sides of the voice coil
loudspeaker's 120 membrane 122 even when the sound generator 100 is
immersed into water.
[0068] In the embodiment illustrated in FIG. 2B, the valve body 131
is configured for the valve head 132 supported by the valve body
131 being positioned at a maximum distance from the plane in which
the loudspeaker 120 is disposed at the casing 110 and opposite this
plane. As can be seen, the valve head 132 is located in the rear
volume 115.
[0069] A third embodiment of the invention is discussed below
referencing FIG. 2C. To avoid any repetitions thereby, only
differences to the above second embodiment are addressed, and for
the rest reference is made to the explanations of the second
embodiment.
[0070] The sound generator 100 according to the third embodiment
differs from the sound generator of the second embodiment in that
the first opening 133 of the valve body's 131 tubing does not open
into the exhaust system but rather into the outside of the casing
110 after penetrating the lower shell 113 of the casing 110. In
this embodiment, the valve body 131 therefore allows for a pressure
compensation between the rear volume 115 and atmosphere.
[0071] In the following, different operating conditions of a sound
generator according to a fourth embodiment of the invention are
discussed referencing FIGS. 3A to 3D. To avoid any repetitions
thereby, only differences to the above second embodiment are
addressed, and for the rest reference is made to the explanations
of the second embodiment.
[0072] The sound generator 100 of the fourth embodiment differs
from the sound generator 100 of the second embodiment in that the
second opening 134 of the valve body 131 has a diameter bigger than
the diameter of the first opening 133 of the valve body 131 but
smaller than the diameter of the valve body 131 in the section 137
having an increased diameter/cross-section between the first
opening 133 and the second opening 134.
[0073] Further, no bell mouth is present inside the casing 110 of
the sound generator 100 according to the fourth embodiment, and the
casing 110 is also not made in two parts by an upper shell and a
lower shell. The casing is rather made cup-shaped from polyvinyl
chloride and is sealed by the loudspeaker basket 123 of the voice
coil loudspeaker 120 supported by the casing 110. This results in
the voice coil loudspeaker 120 separating the rear volume 115
enclosed by the loudspeaker 120 and the casing 110 from the air
114' at the other side of the voice coil loudspeaker 120. Hence,
the rear volume 115 communicates also in this case only through the
pressure compensation valve 130 with air 114' on the other side of
the voice coil loudspeaker 120.
[0074] FIG. 3A illustrates a first operating condition, where only
air 114' surrounds the sound generator 100. A pressure compensation
between the rear volume 115 and the air 114' on the other side of
the voice coil loudspeaker 120 through the pressure compensation
valve 130 is possible without any problems.
[0075] FIG. 3B illustrates a second operating condition, where the
sound generator 100 shown in FIG. 3A is partly immersed into water
(in the Figure illustrated by wiggly lines). In this case a bubble
of compressed air 114' forms in front of the voice coil
loudspeaker's 120 membrane 122.
[0076] FIG. 3C illustrates a third operating condition, where the
sound generator 100 shown in FIG. 3A is completely immersed into
water (in the Figure illustrated by wiggly lines). The air, usually
contained inside the valve body 131, is pushed by the water having
entered into the valve body through the first opening 133 of the
valve body 131 almost completely into the rear volume 115 of the
casing 110 thereby establishing a pressure compensation between the
rear volume 115 and the other side of the voice coil loudspeaker
120 to a certain degree.
[0077] FIG. 3D illustrates a fourth operating condition, where the
sound generator 100 shown in FIG. 3A is canted into water (in the
Figure illustrated by wiggly lines). FIG. 3D thereby shows the
sound generator illustrated in FIG. 3A in a view along direction X.
As can be seen, the first opening 133 of the valve body 131 is
positioned in the tilt axis around which the sound generator 100 is
canted.
[0078] FIG. 4 shows a schematic diagram of a system 7 for
manipulating sound waves propagating through exhaust systems of
vehicles driven by an internal combustion engine, the system
employing the above sound generator 100.
[0079] The sound generator 100 is coupled to an exhaust system 4 in
the region of a discharge opening 5 by a Y-pipe 1. Exhaust gas
traveling through the exhaust system 4 is discharged from the
discharge opening 5 into the exterior together with sound generated
by the sound generator 100.
[0080] An error microphone 8 in the form of a pressure sensor is
provided at the Y-pipe 1. The error microphone 8 measures pressure
variations and thus sound inside the Y-pipe 1 in a section
downstream of a region, where the sound generator 100 is coupled in
fluid communication to the exhaust system 4. It is noted, however,
that the error microphone is only optional.
[0081] The voice coil loudspeaker 120 of the sound generator 100
and the error microphone 8 are electrically connected to a
controller 2. The controller 2 is coupled to an engine controller
of an internal combustion engine 6 by a CAN bus. It is noted that
the present invention is not limited to a CAN bus.
[0082] The exhaust system 4 may further comprise at least one
catalytic converter (not shown) located between the internal
combustion engine 6 and the Y-pipe 1 for cleaning the exhaust gases
emitted from the internal combustion engine 6 that travel through
the exhaust system 4.
[0083] The general operation of the above system 7 for manipulating
sound waves propagating through exhaust systems of vehicles driven
by an internal combustion engine is as follows: Using the sound
measured by the error microphone 8 and/or operating parameters of
the internal combustion engine 6 received via the CAN bus, the
controller 2 calculates control signals using a Filtered-x Least
Mean Squares (FxLMS) algorithm. The control signals enable a
desired manipulation of the sound (exhaust noise) originating from
an operation of the internal combustion engine 6 and propagating
through the interior of the exhaust system 4 by applying engineered
sound produced in the sound generator 100. The controller 2 outputs
these control signals via the control lines to the voice coil
loudspeaker 120 of the sound generator 100.
[0084] Although a system 7 using the sound generator of the first
embodiment for manipulating sound waves propagating through exhaust
systems of vehicles driven by an internal combustion engine has
been described above, alternatively also the sound generator of the
second embodiment which is not in fluid communication with the
exhaust system may be used.
[0085] FIG. 5 shows a schematic illustration of a motor vehicle
having an internal combustion engine 6, an exhaust system 4, and
the above system 7 for manipulating sound waves propagating through
exhaust systems of vehicles driven by an internal combustion
engine. The sound generator and the loudspeakers of the anti-noise
system are not explicitly shown in FIG. 5.
[0086] For the sake of clarity, the Figures show only those
elements, components, and functions that are beneficial for the
understanding of the present invention. Embodiments of the
invention are, however, not limited to the elements, components,
and functions shown, but may comprise further elements, components,
and functions if necessary for their use or scope of functions.
[0087] While the above embodiments of the present invention have
been described by way of example only, it is apparent to those
skilled in the art that numerous modifications, additions and
substitutions can be made without departing from the scope and gist
of the invention disclosed in the following claims. While specific
embodiments of the invention have been shown and described in
detail to illustrate the application of the principles of the
invention, it will be understood that the invention may be embodied
otherwise without departing from such principles.
* * * * *